quote:

Nothing like a little thread drift to keep things going!

Guilty as charged, I have done that to a couple of your post. I feel kind of bad about that, the post on the brakes really rolled off course. I should have started a new post oh well I like yours better.



My setup is the same as yours two pumps, however only one working. All that junk, I'm going to remove the EGR and plug the port can't see any good in recycling exhaust.

Thanks Steve

Hello, Just really enjoying this thread and this site ... THX Barth! I came here because of the below issue ... I am finally home now and am at the point of checking timimg and that is how I got here ... please read below and if you have any thoughts I'd love to hear 'em ...

I have a 1987 Itasca 22' RV with the 454.I had a major power loss while driving on cruise control at about 55 mph thru Idaho last month. Going along just fine and then started slowing on a fairly minor hill ... gave it more throttle and it wouldn't accel until the secondaries on the q-jet kicked in. This problem immediately became chronic and has not improved or gotten worse in 835 miles of limp home driving. Anyway, I turned around and limped the 835 miles back home to Oregon on what I later found to be 5 cylinders firing. At the time of the occurrence I replaced both the carb and chassis fuel filter, plugs, plug wires, cap & rotor. No help at all. Once I got to where I could do something more I found the following:

150# compression on all 8 holes (under 5# difference across the board)

Pulled plug wires one at a time at the distributor and found #s 2, 5, & 8 getting plenty of spark but did not change rpm at all. I then pulled all 3 wires off and to the side ... so with only 5 wires connected the rpm and performance stayed the same.

Starts right up and idles o.k. with 18 inches of vacuum in neutral. Vacuum drops to near zero on any application of throttle. No flutter at all on vacuum guage needle at any time. Believe it or not I can cruise at 60mph showing 5" vacuum and even accelerate somewhat by flooring the pedal to kick in the secondaries, and still got 4.5 mpg. (8 normal)

Anyway, one final note ... about 500 miles into my return home the smog pump rail on the left bank burned a quarter size hole where the 4 small tubes join the larger pipe. Nice noise for the next 7 hours ...

Any thoughts on cause?

... I have not done anything else as yet ... not even pulled the burned smog rail.

The Chevrolet 454 firing order has #5 firing followed immediately by #7 and the normal wire loom will pair theses two plug wires in a parallel path. It can cause misfires or early/late detonation of #7 causing all sorts of hell. The answer is to cross the wires on the loom so that #5 is not next to #7. This makes #5 a long wire that snakes forward then back to its plug. That might explain your problem and mileage. It only requires a look to see. Hope it helps.

Tom's post reminds me that there is a way to connect the plug wires so it looks right, but doesn't run quite right. The "doesn't run quite right" condition isn't as obvious as other miswires, so can be easy to miss.

I have seen this a couple of times, and we all scratched out heads for a while.

Of course, I have never done it myself.

Nope, not me. No Siree.

Plugs in RVs don't get replaced often because of the relatively low mileage. However the extra heat of the location, and the potential for condensation on the engine to deposit rust stains on the plug might cause problems. For me a few years ago, the plugs had under 10K miles. The rig had trouble over 2000 RPM. The plugs looked good, other than the very light rust stain along the ceramic insulator. I could not tell if the ceramic had crazing. But I changed plugs somewhere in PA and the thing ran good again.

I also worry about ethanol in the fuel now, and whether more than the stated 10% is going in, or if old ethanol is breaking down in the RV fuel tank.
Matt

quote:

Originally posted by BarthBluesmobile:

I also worry about ethanol in the fuel now, and whether more than the stated 10% is going in, or if old ethanol is breaking down in the RV fuel tank.
Matt

I'd bet on both.

Another thought................a weak HEI coil can drive you crazy. As can a weak or intermittent module.

A weak coil will only fire the easy cylinders.

Find an old mechanic with an Allen Scope.

My coil is in the cap so should be a simple replacement ... how bad is the r&r on the module?

Not any worse than the coil. The module is in the bottom half of the distributor below the rotor and advance weights (BTW be sure they are free to move). Follow the wires! See diagram below.

The module is screwed to the base plate. (I think you may have to coat the back side with heat transfer paste) easy to swap out.

This is from the 1995 Chev Motorhome manual.. (the 1997 is available on the Barthmobile CD with much other good stuff)

50.) GM HEI Distributor

FROM EXPERIENCE...be sure and use that paste under the module....if you don't you can short it out....

Also, be sure your connections are tight also...

Also, be sure you tighten the 4 screws that hold down the coil...that can short it out...

thanks again everybody ... Steve VW and bill h especially ... I have not been able to find plugs for my exhaust manifolds where the smog rails were attached (4 on each side). The removal required a 7/8 socket and leaves about a 3/4" threaded hole. Any experience with plugs besides welding? Hole threads are good but the flare nuts stripped as they came out. Not pipe thread, a little bigger.

Sorry for the repost, i had a computer glitch and wanted to make sure I at least got my Thank You posted ... thanks again everybody ... Steve VW and bill h especially ... I have not been able to find plugs for my exhaust manifolds where the smog rails were attached (4 on each side). The removal required a 7/8 socket and leaves about a 3/4" threaded hole. Any experience with plugs besides welding? Hole threads are good but the flare nuts stripped as they came out. Not pipe thread, a little bigger.

Sorry can't help you there. Mine had Thorley headers already. The flare fittings were totally gone and threads seized. So I cheated.. (cut off the tubing, hammered a 1/4 brass pipe plug inside each hole and peened the tube over it.) Ugly but OK so far. Good luck!

quote:

Originally posted by fleecerdog:
I have not been able to find plugs for my exhaust manifolds where the smog rails were attached (4 on each side). The removal required a 7/8 socket and leaves about a 3/4" threaded hole. Any experience with plugs besides welding? Hole threads are good but the flare nuts stripped as they came out. Not pipe thread, a little bigger.

You are at the point where Thorleys might be attractive.

No one here or anywhere has ever regretted installing them. If you have dual exhaust, they match right up with band clamps.

whoa! that sounds like a narley fix..

quote:

Originally posted by Steve VW:
Sorry can't help you there. Mine had Thorley headers already. The flare fittings were totally gone and threads seized. So I cheated.. (cut off the tubing, hammered a 1/4 brass pipe plug inside each hole and peened the tube over it.) Ugly but OK so far. Good luck!